Supramolecular Assemblies of Nucleoside Phosphocholine Amphiphiles

Vesicle delivery systems of functional substances for precision nutrition

Vesicular delivery systems are highly ordered assemblies consisting of one or more concentric bilayers formed by the self-assembly of amphiphilic building blocks in the presence of water. In the field of functional food, vesicular delivery systems have been widely explored for effective formulations to deliver functional substances. With the effort of scientific research, certain categories of vesicular delivery systems have successfully been translated from the laboratory to the global market of functional food. This chapter aims to present comprehensively the various vesicular delivery systems, including their design, preparation methods, encapsulation of functional substances, and application in nutritional interventions.

Fibrillar Network Dynamics during Oscillatory Rheology of Supramolecular Gels

Supramolecular gels are three-dimensional network structures formed by the hierarchical self-assembly of small molecules through weak noncovalent interactions. On the basis of the various interactions contributed by specific functional groups/moieties, gels with different architectures can be constructed that are smart to the external stimuli such as pH, type of solvent, stress, temperature, etc. In the present work, we explore the oscillatory shear response of supramolecular self-assembled systems formed by the low-molecular-weight (LMW) gelator based on difunctionalized amino acid, florenylmethoxycarbonyl (Fmoc)-lysine(Fmoc), Fm-K(Fm) in aqueous buffer solution, at two different pH (6 and 7.4). Small amplitude oscillatory shear (SAOS) reported weak frequency dependence of moduli indicating a gel-like network structure. Large amplitude oscillatory shear (LAOS) indicated flow regimes dictated by yielding and subsequent network dynamics analogous to cagelike soft glassy events reported for colloidal systems. The three interval thixotropy test (3iTT) indicated recovery of moduli due to regelation contributed by the reversible interactions. A generalized network model framework is utilized to investigate the transient network characteristics of the Fm-K(Fm) gels. The "network creation" and "network loss" rates were chosen as exponential functions of scaled shear stress (= |τ12(t)G|) to effectively describe the complex response. On the basis of the insights, possible mechanisms to explain the differences/similarities in the response at different pH are speculated. It is further illustrated that the modeling strategy can be extended to supramolecular gels of different classes because of the commonality/universality of their response features under oscillatory shear.

Guanosine-Based Self-Assembly as an Enantioselective Catalyst Scaffold

A self-assembled G-quadruplex formed by guanosine and borate as the chiral scaffold was used to catalyze the asymmetric Friedel-Crafts reaction in water. Catalysis, depending on the self-assembly of guanosine and borate into a fibrillar structure in the presence of Cu²⁺ ions, can be modulated by the assembly concentration, temperature, and amount of Cu²⁺ ions. Detailed spectral experiments proved that the guanosine-based assembly in solution was responsible for the enantioselective catalysis, rather than small-molecule species. Some of the similar G-quartet assemblies were unable to promote the asymmetric reaction, implying unique properties of the current system, including excellent lifetime stability and supramolecular chiral structures. This work provided the first example of the self-assembled G-quadruplex achieving enantioselective catalysis and some perspective to better understand the design of nucleoside-based self-assemblies for an enantioselective reaction. In view of guanosine as a building block, these findings may be applied to discuss the prebiotic chiral catalyst preceded ribozymes.

Programmed Recognition between Complementary Dinucleolipids To Control the Self-Assembly of Lipidic Amphiphiles

One of the major goals in systems chemistry is to create molecular assemblies with emergent properties that are characteristic of life. An interesting approach toward this goal is based on merging different biological building blocks into synthetic systems with properties arising from the combination of their molecular components. The covalent linkage of nucleic acids (or their constituents: nucleotides, nucleosides and nucleobases) with lipids in the same hybrid molecule leads, for example, to the so-called nucleolipids. Herein, we describe nucleolipids with a very short sequence of two nucleobases per lipid, which, in combination with hydrophobic effects promoted by the lipophilic chain, allow control of the self-assembly of lipidic amphiphiles to be achieved. The present work describes a spectroscopic and microscopy study of the structural features and dynamic self-assembly of dinucleolipids that contain adenine or thymine moieties, either pure or in mixtures. This approach leads to different self-assembled nanostructures, which include spherical, rectangular and fibrillar assemblies, as a function of the sequence of nucleobases and chiral effects of the nucleolipids involved. We also show evidence that the resulting architectures can encapsulate hydrophobic molecules, revealing their potential as drug delivery vehicles or as compartments to host interesting chemistries in their interior.

The Why, Where, Who, How, and What of the vesicular delivery systems

Though vesicular delivery systems have been widely explored and reviewed, no comprehensive review exists that covers their development from the inception of the concept to its culmination in the form of regulated marketed formulations. With the advancement of scientific research in the field of nanomedicine, certain category of vesicular delivery systems have successfully reached the global market. Despite extensive research and highly encouraging results in a plethora of pathological conditions in the preclinical studies, translation of these nanomedicines from laboratory to market has been very limited. Aim of this review is to describe comprehensively the various colloidal delivery systems, focusing mainly on their conventional and advanced methods of preparation, different characterization techniques and main success stories of their journey from bench to bedside of the patient. The review also touches the finer nuances of the use of modern formulation approach of DoE (Design of Experiments) in their formulation and the status of regulatory guidelines for the approval of these nanomedicines.

Silver Ions Detection via Nucleolipids Self-Assembly

A novel hybrid bioinspired amphiphile featuring a cytosine moiety, which self-assembles into liposomes can be used to detect silver ions in aqueous media. The coordination of Ag⁺ ions by the nucleotide moiety increases membrane rigidity, which enhances the fluorescence of a common reporter, Thioflavin T. Ag⁺ can be sensed even at trace concentrations (3 ppb) with great specificity over other metals ions. These nucleotide based supramolecular structures can be used to detect silver ions in drinking water, demonstrating the robustness of this approach.

A supramolecular hydrogel prepared from a thymine-containing artificial nucleolipid: study of assembly and lyotropic mesophases

An artificial nucleolipid containing thymine, a triazole-ring, and phosphatidylcholine (TTPC) moieties was prepared by copper catalyzed azide alkyne cycloaddition (CuAAC) under aqueous conditions. The resulting TTPC molecules assembled in situ into a fibrous aggregation. The study of the TTPC fiber assembly using XRD and NMR spectroscopy revealed that the formation of fibers was driven by the unique combination of the lipid and nucleobase moieties in the structure of TTPC. At a critical TTPC concentration, entanglement of the fibers resulted in the formation of a supramolecular hydrogel. Investigation of the lyotropic mesophases in the TTPC supramolecular hydrogel showed the presence of multiple phases including two liquid crystal phases (i.e., nematic and lamellar), which have a certain degree of structural order and are promising templates for constructing functional biomaterials.

Supramolecular Nucleoside-Based Gel: Molecular Dynamics Simulation and Characterization of Its Nanoarchitecture and Self-Assembly Mechanism

Among the diversity of existing supramolecular hydrogels, nucleic acid-based hydrogels are of particular interest for potential drug delivery and tissue engineering applications because of their inherent biocompatibility. Hydrogel performance is directly related to the nanostructure and the self-assembly mechanism of the material, an aspect that is not well-understood for nucleic acid-based hydrogels in general and has not yet been explored for cytosine-based hydrogels in particular. Herein, we use a broad range of experimental characterization techniques along with molecular dynamics (MD) simulation to demonstrate the complementarity and applicability of both approaches for nucleic acid-based gelators in general and propose the self-assembly mechanism for a novel supramolecular gelator, N4-octanoyl-2'-deoxycytidine. The experimental data and the MD simulation are in complete agreement with each other and demonstrate the formation of a hydrophobic core within the fibrillar structures of these mainly water-containing materials. The characterization of the distinct duality of environments in this cytidine-based gel will form the basis for further encapsulation of both small hydrophobic drugs and biopharmaceuticals (proteins and nucleic acids) for drug delivery and tissue engineering applications.

Cytidine- and guanosine-based nucleotide–lipids

A nucleotide–lipids family featuring the four natural nucleobases was explored through their self-assembly properties.

Self-assembly of nucleopeptides to interact with DNAs

As a novel class of biomaterials, nucleopeptides, via the conjugation of nucleobases and peptides, usually self-assemble to form nanofibres driven mainly by hydrogen bonds. Containing nucleobase(s), nucleopeptides have a unique property-interacting with nucleic acids. Here we report the design and characterization of nucleopeptides that self-assemble in water and are able to interact with single-stranded DNAs (ssDNAs). Containing nucleobases on their side chains, these nucleopeptides bind with the ssDNAs, and the ssDNAs reciprocally affect the self-assembly of nucleopeptides. In addition, the interactions between nucleopeptides and ssDNAs also decrease their proteolytic resistance against proteinase K, which further demonstrates the binding with ssDNAs. The nucleopeptides also interact with plasmid DNA and deliver hairpin DNA into cells. This work illustrates a new and rational approach to create soft biomaterials by the integration of nucleobases and peptides to bind with DNA, which may lead to the development of nucleopeptides for controlling DNA in cells.

Plasmonic Chirality Imprinting on Nucleobase-Displaying Supramolecular Nanohelices by Metal-Nucleobase Recognition

Supramolecular self-assembly is an important process that enables the conception of complex structures mimicking biological motifs. Herein, we constructed helical fibrils through chiral self-assembly of nucleobase-peptide conjugates (NPCs), where achiral nucleobases are helically displayed on the surface of fibrils, comparable to polymerized nucleic acids. Selective binding between DNA and the NPC fibrils was observed with fluorescence polarization. Taking advantage of metal-nucleobase recognition, we highlight the possibility of deposition/assembly of plasmonic nanoparticles onto the fibrillar constructs. In this approach, the supramolecular chirality of NPCs can be adaptively imparted to metallic nanoparticles, covering them to generate structures with plasmonic chirality that exhibit significantly improved colloidal stability. The self-assembly of rationally designed NPCs into nanohelices is a promising way to engineer complex, optically diverse nucleobase-derived nanomaterials.

Drug delivery by supramolecular design

Principles rooted in supramolecular chemistry have empowered new and highly functional therapeutics and drug delivery devices. This general approach offers elegant tools rooted in molecular and materials engineered to address the many challenges faced in treating disease.

Probing the Interaction between a DNA Nucleotide (Adenosine-5'-Monophosphate Disodium) and Surface Active Ionic Liquids by Rotational Relaxation Measurement and Fluorescence Correlation Spectroscopy

This article demonstrates the interaction of a deoxyribonucleic acid (DNA) nucleotide, adenosine-5'-monophosphate disodium (AMP) with a cationic surface active ionic liquid (SAIL) 1-dodecyl-3-methylimidazoium chloride (C₁₂mimCl), and an anionic SAIL, 1-butyl-3-methylimidazolium n-octylsulfate ([C₄mim][C₈SO₄]). Dynamic light scattering (DLS) measurements and ¹H NMR (nuclear magnetic resonance) studies indicate that substantial interaction is taking place among the DNA nucleotide (AMP) and the SAILs. Moreover, cryogenic transmission electron microscopy (cryo-TEM) suggests that SAILs containing micellar assemblies are transformed into larger micellar assemblies in the presence of DNA nucleotides. Additionally, the rotational motion of two oppositely charged molecules, rhodamine 6G perchlorate (R6G) and fluorescein sodium salt (Fl-Na), have been monitored in these aggregates. The rotational motion of R6G and Fl-Na differs significantly between SAILs micelles and SAILs-AMP containing larger micellar aggregates. The effect of negatively charged DNA nucleotide (AMP) addition into the cationic and anionic SAILs is more prominent for the cationic charged molecule R6G than that of anionic probe Fl-Na due to the favorable electrostatic interaction between the AMP and cationic R6G. Moreover, the influence of the anionic DNA nucleotide on the cationic and anionic SAIL micelles is monitored through the variation of the lateral diffusion motion of oppositely charged probe molecules (R6G and Fl-Na) inside these aggregates. This variation in diffusion coefficient values also suggests that the interaction pattern of these oppositely charged probes are different within the SAILs-nucleotide containing aggregates. Therefore, both rotational and translational diffusion measurements confirm that the DNA nucleotide (AMP) renders more rigid microenvironment within the micellar solution of SAILs.

Supramolecular gels made from nucleobase, nucleoside and nucleotide analogs

Supramolecular or molecular gels are attractive for various applications, including diagnostics, tissue scaffolding and targeted drug release. Gelators derived from natural products are of particular interest for biomedical purposes, as they are generally biocompatible and stimuli-responsive. The building blocks of nucleic acids (i.e. nucleobases, nucleosides, and nucleotides) are desirable candidates for supramolecular gelation as they readily engage in reversible, noncovalent interactions. In this review, we describe a number of organo- and hydrogels formed through the assembly of nucleosides, nucleotides, and their derivatives. While natural nucleosides and nucleotides generally require derivatization to induce gelation, guanosine and its corresponding nucleotides are well known gelators. This unique gelating ability is due to propensity of the guanine nucleobase to self-associate into stable higher-order assemblies, such as G-ribbons, G4-quartets, and G-quadruplexes.

Stimuli responsive charge-switchable lipids: Capture and release of nucleic acids

Stimuli responsive lipids, which enable control over the formation, transformation, and disruption of supramolecular assemblies, are of interest for biosensing, diagnostics, drug delivery, and basic transmembrane protein studies. In particular, spatiotemporal control over a supramolecular structure can be achieved using light activated compounds to induce significant supramolecular rearrangements. As such, a family of cationic lipids are described which undergo a permanent switch in charge upon exposure to 365 nm ultraviolet (UV) light to enable the capture of negatively charged nucleic acids within the self-assembled supramolecular structure of the lipids and subsequent release of these macromolecules upon exposure to UV light and disruption of the assemblies. The lipids are composed of either two different tripeptide head groups, Lysine-Glycine-Glycine (KGG) and Glycine-Glycine-Glycine (GGG) and three different hydrocarbon chain lengths (C6, C10, or C14) terminated by a UV light responsive 1-(2-nitrophenyl)ethanol (NPE) protected carboxylic acid. The photolysis of the NPE protected lipid is measured as a function of time, and the resulting changes in net molecular charge are observed using zeta potential analysis for each head group and chain length combination. A proof of concept study for the capture and release of both linear DNA (calf thymus) and siRNA is presented using an ethidium bromide quenching assay where a balance between binding affinity and supramolecular stability are found to be the key to optimal nucleic acid capture and release.

Hierarchical self-assembly of switchable nucleolipid supramolecular gels based on environmentally-sensitive fluorescent nucleoside analogs

Exquisite recognition and folding properties have rendered nucleic acids as useful supramolecular synthons for the construction of programmable architectures. Despite their proven applications in nanotechnology, scalability and fabrication of nucleic acid nanostructures still remain a challenge. Here, we describe a novel design strategy to construct new supramolecular nucleolipid synthons by using environmentally-sensitive fluorescent nucleoside analogs, based on 5-(benzofuran-2-yl)uracil and 5-(benzo[b]thiophen-2-yl)uracil cores, as the head group and fatty acids, attached to the ribose sugar, as the lipophilic group. These modified nucleoside-lipid hybrids formed organogels driven by hierarchical structures such as fibers, twisted ribbons, helical ribbons and nanotubes, which depended on the nature of fatty acid chain and nucleobase modification. NMR, single crystal X-ray and powder X-ray diffraction studies revealed the coordinated interplay of various non-covalent interactions invoked by modified nucleobase, sugar and fatty acid chains in setting up the pathway for the gelation process. Importantly, these nucleolipid gels retained or displayed aggregation-induced enhanced emission and their gelation behavior and photophysical properties could be reversibly switched by external stimuli such as temperature, ultrasound and chemicals. Furthermore, the switchable nature of nucleolipid gels to chemical stimuli enabled the selective two channel recognition of fluoride and Hg(2+) ions through visual phase transition and fluorescence change. Fluorescent organogels exhibiting such a combination of useful features is rare, and hence, we expect that this innovative design of fluorescent nucleolipid supramolecular synthons could lead to the emergence of a new family of smart optical materials and probes.

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers.

Supramolecular assemblies of novel aminonucleoside phospholipids and their bonding to nucleic acids

A novel class of aminonucleoside phospholipids has been developed. These molecules could spontaneously assemble into supramolecular structures including multilamellar organization, hydrogels, superhelical strands, and vesicles. Their ability to bind to DNA by hydrogen bonding and π-π stacking interactions was investigated by many means.

Supramolecular hydrogels made of basic biological building blocks

As a consequence of the self-assembly of small organic molecules in water, supramolecular hydrogels are evolving from serendipitous events during organic synthesis to become a new type of materials that hold promise for applications in biomedicine. In this Focus Review, we describe recent advances in the use of basic biological building blocks for creating molecules that act as hydrogelators and the potential applications of the corresponding hydrogels. After introducing the concept of supramolecular hydrogels and defining the scope of this review, we briefly describe the methods for making and characterizing supramolecular hydrogels. We then discuss representative hydrogelators according to the categories of their building blocks, such as amino acids, nucleobases, and saccharides, and highlight the applications of the hydrogels when necessary. Finally, we offer our perspective and outlook on this fast-growing field at the interface of organic chemistry, materials, biology, and medicine. By providing a snapshot for chemists, engineers, and medical scientists, we hope that this Focus Review will contribute to the development of multidisciplinary research on supramolecular hydrogels for a wide range of applications in different fields.

Insights into low molecular mass organic gelators: a focus on drug delivery and tissue engineering applications

In recent years low molecular mass organic gelators (LMOGs) have gained increasing interest as an alternative biomaterial to polymer derived gels, with potential applications in drug delivery and tissue engineering. LMOGs are small organic molecules which self-assemble in water or organic solvents forming a 3D network that entraps the liquid phase resulting in gel formation. In this review, we report the classification of LMOGs into hydrogelators and gelators of organic solvents and we discuss the techniques commonly used to characterise the gels of these gelators with particular reference to specific applications of LMOGs in drug delivery and tissue engineering.

Gelation properties of self-assembling N-acyl modified cytidine derivatives

A new design for a self-assembling gelator of cytidine containing a binary mixture of organic solvent and water, shown to provide a suitable delivery platform for high and low M_w molecules.

Supramolecular hydrogels formed by the conjugates of nucleobases, Arg-Gly-Asp (RGD) peptides, and glucosamine

Here we report the generation of a novel class of supramolecular hydrogelators based on the integration of nucleobase, Arg-Gly-Asp (RGD) peptides, and glucosamine in a single molecule. These novel small molecule hydrogelators self-assemble in water to form stable supramolecular nanofibers/hydrogels and exhibit useful biostability. This approach provides a new opportunity for systematic exploration of the self-assembly of small biomolecules by varying any individual segment to generate a large array of supramolecular hydrogels for biological functions and for biomedical applications.

Charge-reversal lipids, peptide-based lipids, and nucleoside-based lipids for gene delivery

Twenty years after gene therapy was introduced in the clinic, advances in the technique continue to garner headlines as successes pique the interest of clinicians, researchers, and the public. Gene therapy's appeal stems from its potential to revolutionize modern medical therapeutics by offering solutions to myriad diseases through treatments tailored to a specific individual's genetic code. Both viral and non-viral vectors have been used in the clinic, but the low transfection efficiencies when non-viral vectors are used have lead to an increased focus on engineering new gene delivery vectors. To address the challenges facing non-viral or synthetic vectors, specifically lipid-based carriers, we have focused on three main themes throughout our research: (1) The release of the nucleic acid from the carrier will increase gene transfection. (2) The use of biologically inspired designs, such as DNA binding proteins, to create lipids with peptide-based headgroups will improve delivery. (3) Mimicking the natural binding patterns observed within DNA, by using lipids having a nucleoside headgroup, will produce unique supramolecular assembles with high transfection efficiencies. The results presented in this Account demonstrate that engineering the chemical components of the lipid vectors to enhance nucleic acid binding and release kinetics can improve the cellular uptake and transfection efficacy of nucleic acids. Specifically, our research has shown that the incorporation of a charge-reversal moiety to initiate a shift of the lipid from positive to negative net charge improves transfection. In addition, by varying the composition of the spacer (rigid, flexible, short, long, or aromatic) between the cationic headgroup and the hydrophobic chains, we can tailor lipids to interact with different nucleic acids (DNA, RNA, siRNA) and accordingly affect delivery, uptake outcomes, and transfection efficiency. The introduction of a peptide headgroup into the lipid provides a mechanism to affect the binding of the lipid to the nucleic acid, to influence the supramolecular lipoplex structure, and to enhance gene transfection activity. Lastly, we discuss the in vitro successes that we have had when using lipids possessing a nucleoside headgroup to create unique self-assembled structures and to deliver DNA to cells. In this Account, we state our hypotheses and design elements as well as describe the techniques that we have used in our research to provide readers with the tools to characterize and engineer new vectors.

Chemical details on nucleolipid supramolecular architecture: molecular modeling and physicochemical studies

Nucleolipids are currently under investigation as vectors for oligonucleotides (ON) delivery thanks to their supramolecular organization properties and their ability to develop specific interactions (i.e., stacking and potential Watson and Crick hydrogen bonds) for lipoplexes formation. To investigate the factors that govern the interaction events at a molecular level and optimize nucleolipid chemical structures, physicochemical experiments (tensiometry, AFM, BAM, and ellipsometry) combined with molecular dynamics simulation were performed on a series of zwitterionic nucleolipids (PUPC, DPUPC, PAPC) featuring a phosphocholine chain (PC). After construction and initial equilibration, simulations of pure nucleolipid bilayers were run for 100 ns at constant temperature and pressure, and their properties were compared to experimental data and to natural dipalmitoylphosphatidylcholine (DPPC) bilayers. Nucleolipid-based membranes are significantly more ordered and compact than DPPC bilayers mainly due to the presence of many intermolecular interactions between nucleoside polar heads. The hydrophilic phosphocholine moieties connected to the 5' hydroxyls are located above the bilayers, penalizing nucleic bases accessibility for further interactions with ON. Hence, a neutral nucleolipid (PUOH) without hydrophilic phosphocholine was inserted in the membranes. Simulations and experimental analysis of nucleolipid membranes in interaction with a single strand RNA structure indicate that PUOH interacts with ON in the subphase. This study demonstrates that molecular modeling can be used to determine the interactions between oligonucleotide and nucleolipids.

Unexpected bilayer formation in Langmuir films of nucleolipids

Langmuir monolayers have been extensively investigated by various experimental techniques. These studies allowed an in-depth understanding of the molecular conformation in the layer, phase transitions, and the structure of the multilayer. As the monolayer is compressed and the surface pressure is increased beyond a critical value, usually occurring in the minimal closely packed molecular area, the monolayer fractures and/or folds, forming multilayers in a process referred to as collapse. Various mechanisms for monolayer collapse and the resulting reorganization of the film have been proposed, and only a few studies have demonstrated the formation of a bilayer after collapse and with the use of a Ca(2+) solution. In this work, Langmuir isotherms coupled with imaging ellipsometry and polarization modulation infrared reflection absorption spectroscopy were recorded to investigate the air-water interface properties of Langmuir films of anionic nucleolipids. We report for these new molecules the formation of a quasi-hexagonal packing of bilayer domains at a low compression rate, a singular behavior for lipids at the air-water interface that has not yet been documented.

"Molecular trinity" for soft nanomaterials: Integrating nucleobases, amino acids, and glycosides to construct multifunctional hydrogelators

This highlight introduces the development of hydrogelators consisting of nucleobases, amino acids, and glycosides (i.e., molecular trinity), or nucleobases and amino acids (i.e., nucleopeptides). These novel small molecule hydrogelators self-assemble in water to form stable supramolecular nanofibers/hydrogels and exhibit useful biological properties (e.g., biocompatibility, biostability, and the ability to bind and transport DNA into live cells). The approach discussed here not only provides a new strategy to develop soft biomaterials as a form of nanomedicines, but also contributes to the understanding of molecular self-assembly in water by modulating the non-covalent interactions derived from the three basic building blocks used in living organisms.

Catalytic dephosphorylation of adenosine monophosphate (AMP) to form supramolecular nanofibers/hydrogels

The use of enzyme to instruct the self-assembly of the nucleoside of adenosine in water provides a new class of molecular nanofibers/hydrogels as functional soft materials.

Self-assembled nucleolipids: from supramolecular structure to soft nucleic acid and drug delivery devices

This short review aims at presenting some recent illustrative examples of spontaneous nucleolipids self-assembly. High-resolution structural investigations reveal the diversity and complexity of assemblies formed by these bioinspired amphiphiles, resulting from the interplay between aggregation of the lipid chains and base–base interactions. Nucleolipids supramolecular assemblies are promising soft drug delivery systems, particularly for nucleic acids. Regarding prodrugs, squalenoylation is an innovative concept for improving efficacy and delivery of nucleosidic drugs.

Protonation of lipids impacts the supramolecular and biological properties of their self-assembly

We assessed in this work how a chemical structure difference could influence a supramolecular organization and then its biological properties. In our case study, we considered two amphiphilic lipidic gene vectors. The chemical difference was situated on their hydrophilic part which was either a pure neutral thiourea head or a mixture of three thiourea function derivatives, thiourea, iminothiol, and charged iminothiol. This small difference was obtained thanks to the last chemical deprotection conditions of the polar head hydroxyl groups. Light, neutron, and X-ray scattering techniques have been used to investigate the spatial structure of the liposomes and lipoplexes formed by the lipids. The chemical structure difference impacts the supramolecular assemblies of the lipids and with DNA as shown by fluorescence correlation spectroscopy (FCS), X-ray, and neutron scattering. Hence the structures formed were found to be highly different in terms of liposomes to DNA ratio and size and polydispersity of the aggregates. Finally, the transfection and internalization results proved that the differences in the structure of the lipid aggregates fully affect the biological properties of the lipopolythiourea compounds. The lipid containing three functions is a better gene transfection agent than the lipid which only contains one thiourea moiety. As a conclusion, we showed that the conditions of the last chemical step can influence the lipidic supramolecular structure which in turn strongly impacts their biological properties.

Synthesis, characterization, and in vitro transfection activity of charge-reversal amphiphiles for DNA delivery

A series of charge-reversal lipids were synthesized that possess varying chain lengths and end functionalities. These lipids were designed to bind and then release DNA based on a change in electrostatic interaction with DNA. Specifically, a cleavable ester linkage is located at the ends of the hydrocarbon chains. The DNA release from the amphiphile was tuned by altering the length and position of the ester linkage in the hydrophobic chains of the lipids through the preparation of five new amphiphiles. The amphiphiles and corresponding lipoplexes were characterized by DSC, TEM, and X-ray, as well as evaluated for DNA binding and DNA transfection. For one specific charge-reversal lipid, stable lipoplexes of approximately 550 nm were formed, and with this amphiphile, effective in vitro DNA transfection activities was observed.

Novel bolaamphiphilic pyrimidinophane as building block for design of nanosized supramolecular systems with concentration-dependent structural behavior

A new macrocyclic bolaamphiphile with thiocytosine fragments in the molecule (B1) has been synthesized and advanced as perspective platform for the design of soft supramolecular systems. Strong concentration-dependent structural behavior is observed in the water-DMF (20% vol) solution of B1 as revealed by methods of tensiometry, conductometry, dynamic light scattering, and atomic force microscopy. Two breakpoints are observed in the surface tension isotherms. The first one, around 0.002 M, is identified as a critical micelle concentration (cmc), whereas the second critical concentration of 0.01 M is a turning point between the two models of the association involved. Large aggregates of ca. 200 nm are mostly formed beyond the cmc, whereas small micelle-like aggregates exist above 0.01 M. The growth of aggregates between these critical points occurs, resulting in a gel-like behavior. An unusual decrease in the solution pH with concentration takes place, which is assumed to originate from the steric hindrance around the B1 head groups. Because of controllable structural behavior, B1 is assumed to be a candidate for the development of biomimetic catalysts, nanocontainers, drug and gene carriers, etc.